1. Field of the Invention
The present invention relates to a picture displaying apparatus and a method of driving the same. More particularly, the present invention relates to a picture displaying apparatus that does not require an operational circuit for generating a plurality of display data corresponding to different display contents from a single display data when a screen saver function is attained, and a method of driving the same.
2. Description of the Related Art
In recent years, a demand for a display has been remarkably enlarged. In particular, an expectation for a flat panel display represented by a liquid crystal displaying apparatus (LCD), a plasma displaying apparatus (PD) and the like has been increased.
In particular, a self-light-emission type of a picture displaying apparatus, such as an electro-luminescence (EL) and the like, is characterized in that it has a high visual property and an excellent field angle. Also, it has a merit that a back light is unnecessary, differently from the LCD. Moreover, a picture displaying apparatus using an organic electro-luminescence (EL) element is noticeable as a flat display that is also excellent in response performance.
As a method of driving a dot matrix display using such an organic EL element, there are a simple matrix type and an active matrix type.
FIG. 1 is a block diagram showing a conventional simple matrix type of a color organic EL display. This color organic EL display 100 is provided with: a color organic EL display panel 101 of a QVGA class using an NTSC signal; a column driving circuit 102 for sending a signal current to make the color organic EL display panel 101 emit a light at a desirable brightness; a low driving circuit 103 for sending a predetermined voltage while shifting a low electrode in order to perform a Duty drive on the color organic EL display panel 101; and a controller 104 for generating a control signal to control the column driving circuit 102 and the low driving circuit 103.
In the organic EL pixel, if a light is emitted continuously for a long time at the same display condition, a so-called burning is brought about to thereby increase a deterioration in a brightness caused by an element life. For example, in a case of a color organic EL display panel 101 of a portable telephone apparatus, if a clock, a antenna mark, a remaining amount of a battery and the like are always displayed, the deterioration in the brightness of the organic EL pixel corresponding to that portion is especially increased. Thus, if the color organic EL display panel 101 is used in a display such as a portable telephone apparatus, a computer, a car navigation system or the like, it is designed so as to actuate a screen saver function when a wait image plane is displayed or when there is no change in a screen display content for a predetermined period.
In the screen saver state, an display data of a different display content is sent to the color organic EL display panel 101 so that the same display content is not continuously displayed on the color organic EL display panel 101 beyond the predetermined period.
Conventionally, when the display image plane for the screen saver is prepared, the supply of the display data to the color organic EL display panel 101 is carried out as follows.
A first display data corresponding to an display content of one image plane of the color organic EL display panel 101 is stored in advance in ROM (not shown) of the color organic EL display 100. As mentioned above, in the screen saver state, it requires the display data of the different display content. So, conventionally, after the first display data is read from the ROM to RAM (not shown), the controller 104 performs a calculation on the first display data, and generates a second display data as the calculated result. The second display data is generated so as to indicate a different display content for each set time. In the screen saver period, a plurality of second display data are generated which correspond to a plurality of kinds of display contents.
That is, the single first display data is changed by the calculation for each set time. Thus, the second display data of the different display content is generated for each change, and the second display data is sent to the column driving circuit 102. Hence, the different display is displayed on the color organic EL display panel 101 for each set time. Accordingly, the screen saver function is attained.
According to this method, a circuit for calculating the first display data and then generating the second display data is necessary within the controller 104.
Also, apart from the above-mentioned problem, there is a problem that the characteristic difference between the light emitting elements causes a color balance to be deteriorated. That is, in organic EL pixels corresponding to respective three colors of R, G and B, the lives of the elements are different from each other. Thus, even if the screen saver function is uniformly actuated, the development situation of the brightness deterioration is different depending on the color of the light emission. Hence, this causes the color balance to be deteriorated.
When the screen saver function is attained, the picture displaying apparatus, which does not require the above-mentioned calculating circuit, and the method of driving the same are desired.
When the screen saver function is attained, the picture displaying apparatus, which can suppress the above-mentioned deterioration in the color balance to a minimum, and the method of driving the same are desired.
When the screen saver function is attained, the picture displaying apparatus, which does not require the above-mentioned calculating circuit and can suppress the above-mentioned deterioration in the color balance to a minimum, and the method of driving the same are desired.
When the screen saver function is attained, the picture displaying apparatus, which can attain the lower consumptive electric power and does not require the above-mentioned calculating circuit and can suppress the above-mentioned deterioration in the color balance to a minimum, and the method of driving the same are desired.
By the way, Japanese Laid Open Patent Application (JP-A-2000-112435) discloses the following display driving method. In a method of driving a matrix type of a displaying apparatus having a function of setting a part of a region inside a image plane at a display state and setting the other region at a non-display state, at least one of a position of the part of the region set at the display state, an area and an display content is changed at any temporal interval. Accordingly, while a low consumptive electric power property of a partial display is kept, amusingness and originality are given to the image plane at the partial display state.
Also, Japanese Laid Open Patent Application (JP-A-2000-105573) discloses the following displaying apparatus. At a wait state when a power supply is at an on-state and an interrupt signal is not generated, a control is carried out such that a dot displaying unit of an organic EL display is not turned on and only essentially necessary data is displayed for a character displaying unit. Then, if the interrupt signal is generated, the display corresponding to the data input from a key board or an input/output circuit is displayed only for a predetermined display period. Accordingly, the lower consumptive electric power of the displaying apparatus is attained without any loss of convenience.
Moreover, Japanese Laid Open Patent Application (JP-A-Heisei, 8-254964) discloses the following electrical field radiation color displaying apparatus. The electrical field radiation color displaying apparatus including a frame memory for storing a picture data formatted for a frame sequence display is provided with: a unit for switching the display between a usual electric power consumption mode and a reduced electric power consumption mode; a unit for providing a single color display if the display is at the reduced electric power consumption mode; and a unit for bypassing the frame memory if the single color display is provided. Also, Japanese Laid Open Patent Application (JP-A-Heisei, 8-254964) discloses the following content. An electrical field radiation color display electronic system includes a unit for reducing an electric power. The displaying system includes a voltage switching type of a three-color anode plate and an emitter plate by which an address in a form of matrix can be specified. In the reduced electric power consumption mode, the display is switched from a color mode to a single color mode. By using the unit for reducing the electric power, a bright information for green (carrying a single color picture information) bypasses the frame memory, and it is directly coupled to a second multiplexer through a three-state buffer from a first multiplexer. The buffer carries out an insulation separation of a bypass line at a time of a color operation of the display. In the frame memory, it can be bypassed at the time of the single color operation. Thus, since the frame memory can be set at a wait mode, an electric power of about 1 W can be reduced.
Japanese Laid Open Patent Application (JP-A-Showa, 61-264876) discloses the following picture displaying apparatus. This is provided with: a screen on which a fluorescent material emitting a light when an electronic beam is radiated is coated; an electronic beam source for generating the electronic beam for each vertical block after an image plane on the screen is divided into a plurality of blocks in a vertical direction; a separating unit for separating the electronic beam generated by the electronic beam source for each horizontal block after the electronic beam is divided into a plurality of horizontal blocks; a polarization electrode for polarizing the electronic beam at a plurality of stages in a vertical direction and a horizontal direction between the electronic beam source and the screen; a beam flow control electrode for controlling an amount at which the electronic beam separated for each horizontal block is radiated to the screen and controlling a light emission amount of each pixel on the image plane of the screen; a focusing electrode for controlling the light emission size on the surface of the fluorescent material through the electronic beam in each pixel; a rear electrode for controlling the amount of the electronic beams from the electronic beam source; and an acceleration electrode for accelerating the electronic beam and radiating it to the screen. Also, this is provided with a unit for dividing the beam flow control electrode into the upper portion and the lower portion in the vertical direction at a location corresponding to a position at which the number of horizontally scanning lines is divided into two components and applying the signals, which are deviated by ½ fields, to the respective upper and lower beam flow control electrodes, in the line order corresponding to a horizontal synchronization.